Gasoline containing dialkanolamine boronic acid bis-esters



Unite States Patent 3,021,206 GASOLINE CONTAINING DIALKANOLAMINE BORONIC ACID BIS-ESTERS Stephen J. Groszos, Cincinnati, Ohio, and Clyde S. Scanley, Stamford, Conn., assignors to American Cyanamid Company, New York, N.Y., a corporation of Maine No Drawing. Filed Aug. 7, 1959, Ser. No. 832,159

' 9 Claims. (Cl. 44-75) This invention relates to liquid hydrocarbon motor fuels of the type used in internal combustion engines, such fuels being hereinafter referred to as gasoline, and more particularly to the provision of a novel class of antiknock agents therefor.

Heretofore the principal antiknock agent used in gasoline has been tetraethyl lead. This compound is very effective but it is a cumulative poison and therefore the quantities that can be added have been strictly limited. Not more than 3 cc. per gallon of tetraethyl lead may be added to gasoline, this quantity being equivalent to 0.15% by weight, and ordinarily the common level of addition is 2 cc. per gallon. It is a principal object of the present invention to provide a class of antiknock agents that do not have the poisonous character of organic lead compounds and which therefore can be used in gasoline in unrestricted amounts. A further object is the provision of a class of effective antiknock agents that can be readily and cheaply prepared from commercially available raw materials. Still further objects of the invention will be apparent from the following description thereof when taken with the specific examples and the appended claims.

In accordance with the invention, boronic acid bisesters of certain dialkanolamines are incorporated into gasoline in antiknock quantities; i.e., in the quantities in which effective antiknock agents are ordinarily employed. Such quantities usually range from about 0.02% to 0.25% by weight, although larger quantities of the boronic acid bis-esters can be used in some cases without harm. The dialkanolamines with which boronic acids are esterified to prepare the antiknock agents of the invention are the 2-hydroxy and 3-hydroxy compounds; that is to say, the unsubstituted and substituted diethanolamines and dipropanolamines. We have found that these amines form cyclic bis-esters with boronic acids which are soluble in volatile petroleum hydrocarbon fuels of the type used as gasoline and are effective antiknock agents when incorporated therein in quantities within the range indicated above.

The boronic acids to be used in preparing antiknock agents included within the scope of our invention may contain, as the organic substituent attached to boron, either an aliphatic or an aromatic radical. Thus, alkyl boronic acids in which the alkyl radical contains from 1 to 18 or more carbon atoms may be used. Likewise, aliphatic hydrocarbon substituents of the olefin series may be present. Phenyl boronic acids that may be used include phenyl boronic acid itself (C H B(OH) or such homologs as the tolyl boronic acids, xylyl boronic acids and the like.

Among the dialkanolamines that may be used as esterifying alcohols are diethanolamine and di-n-propanolamine themselves and alkyl-substituted diethanolamines and dipropanolamines in which alkyl radicals of from 1 to 16 carbon atoms are attached to the ethanol or propanol groups such as diisopropanolamine, di-sec.-butanolamine (bis-(2-hydroxybutyl) amine) di-2-hexylethanolamine and the like. N-substituted diethanolamines and dipropanolamines in which the N-substituent is a hydrocarbon radical of the aliphatic or mononuclear aromatic series may also be used. Thus, N-ethyl-diethanolamine, N-butyldiethanolamine, N-octyl-diethanolamine, N-octadecyl-diice ethanolamine or the corresponding propanolamines may be used.

It is an important advantage that the esterification of these diethanolamines with boronic acids is easily carried out by well known esterifying procedures, and that good yields of the esters are obtained. For example the dialkanolamine and boronic acid may be suspended in an organic solvent and heated with distillation of water until the bis-ester is formed. Advantageously, a solvent capable of forming an azeotrope with water may be used such as benzene, toluene, xylenes and the like. Most of the bis-esters are crystalline compounds that have the added advantage of hydrolytic stability; i.e., they do not hydrolyze in the presence of water and therefore are not deteriorated by any water that may be present during storage of gasoline treated therewith.

It will be understood that the dialkanolamine boronates may be used in gasoline which contains other ingredients than the fuel itself. Thus they may be used in gasolines containing antioxidants, inhibitors such as copper-chelating compounds, tetraethyl lead and other antiknock additives, dyestufis and the like. They may also be used in gasolines containing a variety of fuel ingredients such as aromatic and hydroaromatic hydrocarbons boiling in the gasoline range, alcohol and the like.

The invention will be further described and illustrated by the following specific examples, wherein particular gasoline compositions are evaluated. Since the methods of preparation of many of the dialkanolamine boronates used in these examples are not readily available in the literature their preparation is also described. It should be understood, however, that the invention in its broader asspects is not limited to the particular subject matter of the examples, but is to be construed within the scope of the appended claims.

Example 1 Iminodiethyl-n-hexylboronate was prepared by distilling under nitrogen a solution of 13 grams (0.1 mol) of n hexylboronic acid and 10.5 grams (0.1 mol) of diethanol amine in ml. of dry toluene until the water of condensation was removed. The white needles that separated on cooling were recrystallized from-benzene. After a second recrystallization from an acetone-petroleum ether mixture a product melting at 128-129 C. was obtained.

To a gasoline containing no other antiknock additive and having an octane number of 80.3 there was added 0.08% by weight of the iminodiethyl-n-hexylboronate and the ASTM motor octane number was determined by the motor method (ASTM-D357). The octane number of the treated fuel was 82.3.

Example 2 A solution of 10.2 grams (0.1 mol) of n-butylboronic acid and 10.5 grams (0.1 mol) of diethanolamine in 150 ml. of dry toluene was distilled until the water of con: densation was removed. The resulting 'im'inodiethyl-nbutylboronate was recovered and dissolved in another portion of the gasoline of Example 1 to a concentration of 0.1%. The octane number of the solution was 83.2.

Example 3 Secondary butylboronic acid was prepared by reacting a preparation of 0.55 gram mole of sec.-butylmagnesium iodide in 250 ml. of anhydrous ether with 60 grams (0.55 mol) of trimethyl borate. The moist ethereal solution of the acid was stripped of ether, 300 ml. of toluene was added and the water was removed by distilling in a nitrogen atmosphere. There was then added 50 grams of diethanolamine and the removal of water was repeated. The product after purification as described in Example 1 was tested in a sample of the gasoline of that example at a concentration of 0.16% by weight. number of the treated gasoline was 82.2.

Example 4 Phenylboronic acid is prepared by condensing bromobenzene with an alkyl bo'rate by the Grignard reaction. The following procedure was used.

A. small proportion of the butylborate (25 m1. of a total of 1085 ml, which was 920 grams or 4 mols) was added to 24.32 grams of magnesium in a 2-liter flask, taking precautions to exclude moisture. A crystal of iodine was introduced to start the reaction and a small proportion of the bromobenzene (the total of which was 1 57 grams or 1 mol-) was added andthe mixture was heated. When the purple iodine color disappeared at 120 C. stirring was started and the remaining butyl borate. and bromobenzene were added slowly and separately.

The mixture was boiled under reflux at 288 C. for several hours until the solution became viscous and the color intensified. It was then cooled and the resulting hard, sticky solid was hydrolyzed. by adding dilute aqueous HCl at room temperature. The organic layer was ex.- t-ractedi with dilute. aqueous NaOI-L solution which was then neutralized with acid. The phenylboronic acid erys tailized. from: theresulting aqueous solutiont The esters of phenylboronic acid: are prepared by charging the acid or its anhydride (C H BO) together with: the esterifying. alcohol. and an azeotroping solvent such: as benzene or toluene to areaction flask and heat ing with distillation until. water evolution. is complete. The. following esters were. prepared by this. procedure.

(1.) Z-phenyl-1,3 dioxa-6-azaa2-boracyclooctane of the formula 0' ant-en,

NH 0 ens-on,

from phenylboronic. anhydride and diethanolami'ne. When tested. in a gasoline having an octane; number of 80.3..- in a. quantity of 0.15% by: weight by the; ASTM' D357 motor test. theoctane. number of the treated gasoline was 82.3.

(.2.)v 2-phenyl-4-,8.-dimethyl.--1,3; diosr .-6- -aza-'2-boracyclooctane of the: formulav r coir-old, (kHz-B 1 NH eon-c from triphenylboroxole: and diisopropanolamine. When tested in the same gasoline at a concentration of. 0.12% the, octane number was8119.

(3), 2'-phenyl'-6-'ethyl-'1,3-dioxa-6-aza-2-boracyclooctane of the formula N .CzH'; corn-o 2 from triphenylboroxole, and N-ethyldiethanolamine. When tested. in the same gasoline. at. a. concentration. of (1.2% theoctane number. was. 82.2.

The octane (4) Phenylboronic acid-N-ethyl-di n propanolamine condensation product of the probable formula NCrHt C(GHfis This was prepared by charging a reaction flask with 12.2 grams (0.1 mol) of phenylboronic acid, 16.1 grams (0.1 mol) of N-ethyl-di-n-propanolamine and ml. of solvent, heating to boiling and distilling a toluene-water azeotrope until 4 ml. of water was collected. After removing most of the remaining toluene by distillation the solution was cooled and a tacky, amber glass separated out. When treated in a sample of the same gasoline at 0.1% concentration the octane number was 81.1.

(5) Imino-di-n-propYl phenylboronate of the formula oust-B NH O(CH2)a prepared from phenylboronic acid and di-n-propanolamine by dehydration in toluene. When a sample of this product'was tested in the same gasoline at a concentration of 0.06% by weight the octane number was 80.8. This corresponds to an: increase in octane number of 0.8 for each 0.1% or the boronic acid ester added to the gasoline- What we claim is: 7

1. Gasoline containing boronic acid bis-ester of a member of the group consisting of 2-hydroxy and 3-l1ydroxy dialkanolamines, said ester being, further derived froman acid selected from the group consisting of a liphatic. hydrocarbon boronic acid and aryl boronic acid, and said ester being present in antiknock quantities.

2. Gasoline containing alkylboronic acid bis-ester of a member of the group consisting. of 2-hydroxy and 3-hydroxy dialkanolamines, said ester being present in antiknock quantities.

3'. Gasoline containing boronic acid bis-ester of a diethanolamine, said ester being further derived from an acid selected from the group consisting of aliphatic hyd'rocarbon boronic acid and ar'yl' boronic acid, and said ester being present in antiknock quantities.

4. Gasoline containing an antiknock quantity of iminodiethyl alkylboronate'.

5. Gasoline containing an antiknock quantity of iminodiethyl phenylboronate.

6 Gasoline containing an antiknock. quantity of iminodiethylbutylboronate.

7. Gasoline containing an antiknock quantity of iminodiethyl hexylboronate.

8. Gasoline containing boronic acid bis-ester of a dipropanolamine, said ester being further derived from an acid selected from the group consisting of aliphatic hy drocarbon boronic acid and aryl boronic acid, and said ester being present in antiknock quantities.

9. Gasoline containing arylboronic acid bis=ester of a member of the groupconsisting of Z-hydroxy and 3-hydroxy dialkanolarnines, said ester being present in antiknock quantities.

References Cited in the tile of this patent UNITED STATES PATENTS 

1. GASOLINE CONTAINING BORONIC ACID BIS-ESTER OF A MEMBER OF THE GROUP CONSISTING OF 2-HYDROXY AND 3-HYDROXY DIALKANOLAMINES, SAID ESTER BEING FURTHER DERIVED FROM AN ACID SELECTED FROM THE GROUP CONSISTING OF ALID PHATIC HYDROCARBON BORONIC ACID AND ARYL BORONIC ACID, AND SAID ESTER BEING PRESENT IN ANTIKNOCK QUANTITIES. 